Robust stator winding temperature sensor

ABSTRACT

Disclosed herein, among other things, is a stator winding temperature sensor. According to an embodiment, the sensor includes at least one sensing wire coil adapted to be connected to a stator. The sensor also includes a body, including a core material surrounding at least a portion of the sensing wire coil, and a laminate material over the core material. The body has a thickness adapted to protect the sensing wire coil. The sensor includes a lead wire adapted to connect to an external monitoring device. The sensing wire coil is electrically connected to the lead wire at a lead step portion of the sensor. In addition, the sensor includes a tab extending from the lead wire and encompassing the lead step. The tab protects the lead step and the sensing wire coil in a region where the sensor extends over an end of the stator.

RELATED APPLICATIONS

This application is related to and hereby claims the priority benefit ofU.S. Provisional Patent Application No. 60/950,066 filed Jul. 16, 2007and entitled “ROBUST STATOR WINDING TEMPERATURE SENSOR”, whichapplication is incorporated herein by reference in its entirety.

TECHNICAL FIELD

This disclosure relates generally to temperature sensors, and moreparticularly to systems and methods for robust temperature measurementof motor and generator stator windings.

BACKGROUND

A resistance-based temperature sensor, or resistance temperaturedetection element (RTD), can be used in a number of applications tomeasure operating temperature based on a sensed change in resistance inone or more wires incorporated into the sensor. When connected to astator, an RTD can be used to detect temperatures in the windings,airstreams, and gas streams of motors, generators, and auxiliaryequipment.

To connect an RTD to a stator, the RTD is installed between coils orwindings inside the stator. The RTD may be installed completely inside aslot with only insulated wires protruding past the edge of the statorcore. This type of RTD combines a thin fiberglass body material withrelatively large leads that do not fit inside the fiberglass body,requiring a “lead step” of fiberglass material be manufactured on thelead wire end. The resulting combination of this fiberglass with a leadstep makes the RTD's installation process and positioning inside a motoror generator different than other applications and susceptible to damageduring motor or generator manufacturing. What is needed is a robuststator winding temperature sensor.

SUMMARY

Disclosed herein, among other things, is a stator winding temperaturesensor. According to an embodiment, the sensor includes at least onesensing wire coil. The sensing wire coil is adapted to be connected to astator to sense temperature of the stator. The sensor embodiment alsoincludes a fiberglass body, including a core material surrounding atleast a portion of the sensing wire coil, and an epoxy laminate materialover the core material. The fiberglass body has a thickness adapted toprotect the sensing wire coil. The sensor embodiment further includes alead wire adapted to connect to an external monitoring device. A leadstep portion of the sensor is where the sensing wire coil iselectrically connected to the lead wire. In addition, the sensorembodiment includes a tab extending from the lead wire and encompassingthe lead step. The tab protects the lead step and the sensing wire coilin a region where the sensor extends over an end of the stator.

Disclosed herein, among other things, is a system using an externalmonitoring device for measuring motor or generator operatingtemperature. The system includes a stator winding temperature sensorfriction fit to the stator. The sensor includes a sensor body housingone or more sensor wires and a lead wire electrically connected to thesensor wires and adapted to connect to the external monitoring device.An elongated tab extends from the lead wire and encompasses a portion ofthe sensor wires in a region where the sensor wires extend over an endof the stator.

Disclosed herein, among other things, is a method for manufacturing atemperature sensor for sensing temperature of a stator. A sensing wirecoil is fitted to the stator to sense temperature of the stator. Atleast a portion of the sensing wire coil is surrounded with a fiberglassbody having a core material and an epoxy laminate material over the corematerial. A lead wire is electrically connected to an externalmonitoring device. The sensing wire coil is electrically connected tothe lead wire at a lead step. A tab is provided extending from the leadwire and encompassing the lead step to protect the lead step and thesensing wire coil in a region where the sensor extends over an end ofthe stator.

This Summary is an overview of some of the teachings of the presentapplication and not intended to be an exclusive or exhaustive treatmentof the present subject matter. Further details about the present subjectmatter are found in the detailed description and appended claims. Thescope of the present invention is defined by the appended claims andtheir legal equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates a schematic diagram of a stator winding temperaturesensor.

FIG. 1B illustrates a schematic diagram of a top view of a statorwinding temperature sensor, according to an embodiment of the presentsubject matter.

FIG. 1C illustrates a schematic diagram of a side view of a statorwinding temperature sensor, according to an embodiment of the presentsubject matter.

FIG. 2A illustrates a diagram of a stator winding temperature sensor,showing structural strength of regions of the sensor.

FIG. 2B illustrates a diagram of a stator winding temperature sensor,showing structural strength of regions of the sensor, according to anembodiment of the present subject matter.

FIG. 3A illustrates a schematic diagram of a body portion of a statorwinding temperature sensor.

FIG. 3B illustrates a schematic diagram of a body portion of a statorwinding temperature sensor, according to an embodiment of the presentsubject matter.

FIG. 4 illustrates an end-view of a system including a stator windingtemperature sensor, according to an embodiment of the present subjectmatter.

FIG. 5 illustrates a side-view of a system including a stator windingtemperature sensor, according to an embodiment of the present subjectmatter.

DETAILED DESCRIPTION

The following detailed description of the present subject matter refersto subject matter in the accompanying drawings which show, by way ofillustration, specific aspects and embodiments in which the presentsubject matter may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice thepresent subject matter. References to “an”, “one”, or “various”embodiments in this disclosure are not necessarily to the sameembodiment, and such references contemplate more than one embodiment.The following detailed description is demonstrative and not to be takenin a limiting sense. The scope of the present subject matter is definedby the appended claims, along with the full scope of legal equivalentsto which such claims are entitled.

A resistance-based temperature sensor, or resistance temperaturedetection element (RTD), can be used in a number of applications tomeasure operating temperature based on a sensed change in resistance inone or more wires incorporated into the sensor. When connected to astator, an RTD can be used to detect temperatures in the windings,airstreams, and gas streams of motors, generators, and auxiliaryequipment.

To connect an RTD to a stator, the RTD is installed between coils orwindings inside the stator. The RTD may be installed completely inside aslot with only insulated wires protruding past the edge of the statorcore. This type of RTD combines a thin fiberglass body material withrelatively large leads that do not fit inside the fiberglass body,requiring a “lead step” of fiberglass material be manufactured on thelead wire end. The resulting combination of this fiberglass with a leadstep makes the RTD's installation process and positioning inside a motoror generator different than other applications and susceptible to damageduring motor or generator manufacturing.

Other stator RTDs exhibited tensile failures during installation andmanufacturing, as RTDs are friction fit to the stator windings. Thecause of these failures can be linked to stress on the RTD sensing wirecaused by the installation process, which can include pressure, blowswith rubber mallets, and bending of the lead end/lead step area of theRTD at the edge of the stator core. FIG. 1A illustrates a schematicdiagram of a stator winding temperature sensor 100. A primary area offailure 105 is shown, including a lead step 120 connecting lead wires135 with plotted elements (thin wire coils for sensing) 130. The tab 110does not protect the lead step 120, nor does it protect othersignificant portions of the primary failure area 105. FIG. 2Aillustrates a diagram of a stator winding temperature sensor 200,showing structural strengths (and weaknesses) of regions of the sensor.Element wire section 205 breaks at 70-80 pounds per square inch (PSI),element wire sections 215 and 220 breaks at 60 PSI, fiberglass section210 is good to 80 PSI, while fiberglass section 230 crushes at 60 PSI.Tab section 240 does not protect the element wire section 215. FIG. 3Aillustrates a schematic diagram of a body portion 300 of a statorwinding temperature sensor. Plotted element (sensing wire) 305 issurrounded by a thickness of core material 320, which has surroundinglayers of epoxy laminate 310. The overall thickness 330 of the bodyportion is 0.030 inches. The 0.030 inch thick fiberglass body, when usedwith an 18 gage wire lead step, makes the part susceptible to damage ofthe small diameter sensing coil (plotted element). The sensor is bentaround the edge of the stator core during installation and operation, asthe sensors are placed over and under the stator coils. What is neededis a robust stator winding temperature sensor.

Various embodiments of the present subject matter are related to statorwinding temperature sensors. These sensors are connected to coils orwindings of stators in motors, generators, and auxiliary equipment tosense temperature. A “pinch zone” exists where the sensor exits the coreof the motor or generator, at the end of the stator. The present subjectmatter provides for elongated tabs to protect the small diameter sensingwire in the vicinity of the pinch zone. The elongated tab is part of thesensor subassembly and repositions the small diameter sensing wire awayfrom the susceptible areas of damage. The elongated tab technique alsomakes the position of the tab to sensing wire joint visible by movingthis joint out from under the lead step area. This feature enables motorand generator assemblers to consistently position the RTD sensor andavoid hitting the coils in the vulnerable area. The overall sensor isthus stronger and provides a visible joint location to allow for moreprecise installation, further reducing the likelihood of damage andsensor failure.

A “strike zone” exists along a slot under the coils of the stator wherethe sensor is placed and struck with a mallet, to physically connect thesensor into the slots. This portion of the RTD sensor is currentlysubject to damage when the coils are struck to wedge the coils intoplace inside the motor or generator stator slot. The damage causeslocalized tensile failures in the relatively small diameter sensing wireinside the sensor. The 0.030 inch thick fiberglass body is too thin toprovide adequate protection, and thus these parts fail. The presentsubject matter provides for a more robust sensor body, or thicker layerof material over the sensor, in the strike zone and the pinch zone toprotect the small diameter sensing wire. According to an embodiment, a0.040 inch thick fiberglass body is used to provide more protection tothe sensing wire. Testing of the sensors has provided the followingdata:

Pressure Wire Damage/RTD Failure Fiberglass Damage Applied .030″ thick.040″ thick .030″ thick .040″ thick 40 psi No No No No 60 psi Yes No NoNo 80 psi Yes No No No 100 psi  Yes No No No 120 psi  Yes No Yes Yes

This shows that the present subject matter increases the strength of theinternal sensing wires to at least 120 PSI. In addition, externalfiberglass damage is visible before damage to the internal sensing wiresis sustained. This allows for detection of over-stressing the sensor andfacilitates process improvement and prevention of future damage. Becauseend users typically provide an upper limit to the thickness of thesensor body (limited by the dimensions of the stator openings), thethickness of the protective material around the sensing wires islimited.

Disclosed herein, among other things, is a stator winding temperaturesensor. According to an embodiment, the sensor includes at least onesensing wire coil. The sensing wire coil includes platinum wires, in anembodiment. The sensing wire coil is adapted to be connected to a statorto sense temperature of the stator (of a motor or generator, forexample). The sensor embodiment also includes a fiberglass body,including a core material surrounding at least a portion of the sensingwire coil, and an epoxy laminate material over the core material. Thefiberglass body has a thickness adapted to protect the sensing wirecoil. According to an embodiment, the fiberglass body has a thickness of0.040 inches to protect the sensing wire coil in the pinch zone and thestrike zone. The sensor embodiment further includes a lead wire adaptedto connect to an external monitoring device. The lead wire includes an18 gage lead wire, in an embodiment. A lead step portion of the sensoris where the sensing wire coil is electrically connected to the leadwire. In addition, the sensor embodiment includes a tab extending fromthe lead wire and encompassing the lead step. The tab protects the leadstep and the sensing wire coil in a region where the sensor extends overan end of the stator. According to an embodiment, the tab section is2.375 inches in length to protect the sensing wire coil in the pinchzone.

FIG. 1B illustrates a schematic diagram of a top view of a statorwinding temperature sensor 150, according to an embodiment of thepresent subject matter. A primary area of failure 155 is shown,including a lead step 120 connecting lead wires 135 with plottedelements (thin wire coils for sensing) 130. The tab 160 protects thelead step 120, plus other significant portions of the primary failurearea 155. FIG. 1C illustrates a schematic diagram of a side view of astator winding temperature sensor, according to an embodiment of thepresent subject matter. The lead step 120 and primary area of failures155 are shown within the proposed tab length 160.

FIG. 2B illustrates a diagram of a stator winding temperature sensor250, showing structural strength of regions of the sensor, according toan embodiment of the present subject matter. A body thickness of 0.040inches and tab length of 2.375 inches are used in this embodiment.Element wire sections 255 and 295 are good (no breaks) up to 120 PSI,element wire section 265 breaks at 80 PSI, element wire is moved out ofsection 270 in this embodiment, fiberglass section 260 is good to110-120 PSI, while fiberglass section 280 crushes at 60 PSI. Elongatedtab section 290 provides protection for the element wire sections, andthe increased body thickness likewise provides protection to reducefailures.

FIG. 3B illustrates a schematic diagram of a body portion 350 of astator winding temperature sensor, according to an embodiment of thepresent subject matter. Plotted element (sensing wire) 355 is surroundedby a thickness of core material 370, which has surrounding layers ofepoxy laminate 360. The overall thickness 380 of the body portion is0.040 inches, in the depicted embodiment. Other thicknesses may be usedwithout departing from the scope of this disclosure.

FIG. 4 illustrates an end-view of a system including a stator windingtemperature sensor 400, according to an embodiment of the presentsubject matter. Sensor lead wires 420 are shown extending beyond the endof stator 410. FIG. 5 illustrates a side-view of a system including astator winding temperature sensor 500, according to an embodiment of thepresent subject matter. Sensor lead wires 510 are shown connected tosensor bodies 520, the bodies housing smaller diameter sensing wires,such as platinum wires in an embodiment. The tab 530 protects thesensing wires in the vicinity of the end of the stator, or pinch zone.According to an embodiment, the stator winding temperature sensor shownin FIGS. 4 and 5 has a tab as depicted in FIG. 1B and body as depictedin FIG. 3B.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement which is calculated to achieve the same purpose maybe substituted for the specific embodiment shown. It is to be understoodthat the above description is intended to be illustrative, and notrestrictive. The scope of the present subject matter should bedetermined with reference to the appended claims, along with the fullscope of equivalents to which such claims are entitled.

1. A temperature sensor for sensing temperature of a stator andcommunicating the sensed temperature to an external monitoring device,comprising: at least one sensing wire coil, the sensing wire coiladapted to be fit to the stator and adapted to sense temperature of thestator; a fiberglass body, including: a core material surrounding atleast a portion of the sensing wire coil; and an epoxy laminate materialover the core material; a lead wire adapted to connect to the externalmonitoring device; a lead step where the sensing wire coil iselectrically connected to the lead wire; and a tab extending from thelead wire and encompassing the lead step, wherein the tab protects thelead step and the sensing wire coil in a region where the sensor extendsover an end of the stator.
 2. The sensor of claim 1, wherein the atleast one sensing wire coil includes a platinum sensing wire coil. 3.The sensor of claim 1, wherein the sensing wire coil is adapted to befriction fit to a stator.
 4. The sensor of claim 1, wherein a thicknessof the fiberglass body is approximately 0.04 inches.
 5. The sensor ofclaim 1, wherein a thickness of the fiberglass body is greater thanapproximately 0.04 inches.
 6. The sensor of claim 1, wherein the leadwire includes an 18 gage lead wire.
 7. The sensor of claim 1, wherein alength of the tab is approximately 2.375 inches.
 8. A system using anexternal monitoring device for measuring operating temperature of amotor or generator having a stator, comprising: a stator windingtemperature sensor friction fit to the stator, the sensor including asensor body housing one or more sensor wires; a lead wire electricallyconnected to the sensor wires and adapted to connect to the externalmonitoring device; and an elongated tab extending from the lead wire andencompassing a portion of the sensor wires in a region where the sensorwires extend over an end of the stator.
 9. The system of claim 8,wherein the stator winding temperature sensor is adapted to measureoperating temperature of the stator based on a sensed change inresistance in the one or more sensor wires.
 10. The system of claim 8,wherein the lead wire includes an 18 gage lead wire.
 11. The system ofclaim 8, wherein a length of the elongated tab is approximately 2.375inches.
 12. The system of claim 8, wherein a length of the elongated tabis greater than approximately 2.375 inches.
 13. The system of claim 8,wherein the at least one sensor wire includes a platinum sensor wire.14. The system of claim 8, wherein the external monitoring deviceincludes a personal computer.
 15. A method for manufacturing atemperature sensor for sensing temperature of a stator, comprising:fitting a sensing wire coil to the stator to sense temperature of thestator; surrounding at least a portion of the sensing wire coil with afiberglass body having a core material and an epoxy laminate materialover the core material; electrically connecting a lead wire to anexternal monitoring device; electrically connecting the sensing wirecoil to the lead wire at a lead step; and providing an elongated tabextending from the lead wire and encompassing the lead step to protectthe lead step and the sensing wire coil in a region where the sensorextends over an end of the stator.
 16. The method of claim 15, whereinfitting a sensing wire coil to the stator includes friction fitting thesensing wire coil to the stator.
 17. The method of claim 15, whereinfitting a sensing wire coil to the stator includes fitting a platinumsensing wire coil to the stator.
 18. The method of claim 15, whereinsurrounding at least a portion of the sensing wire coil with afiberglass body includes surrounding the coil with a fiberglass bodyhaving a thickness of greater than approximately 0.04 inches.
 19. Themethod of claim 15, wherein electrically connecting a lead wire includeselectrically connecting an 18 gage lead wire.
 20. The method of claim15, wherein providing an elongated tab includes providing a tab having alength of at least approximately 2.375 inches.